/*
 * FreeRTOS Kernel V10.4.6
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.    All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */

/*
 * A sample implementation of pvPortMalloc() and vPortFree() that permits
 * allocated blocks to be freed, but does not combine adjacent free blocks
 * into a single larger block (and so will fragment memory).    See heap_4.c for
 * an equivalent that does combine adjacent blocks into single larger blocks.
 *
 * See heap_1.c, heap_3.c and heap_4.c for alternative implementations, and the
 * memory management pages of https://www.FreeRTOS.org for more information.
 */
#include <stdlib.h>

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
 * all the API functions to use the MPU wrappers.    That should only be done when
 * task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

#include "FreeRTOS.h"
#include "task.h"

#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE

#if ( configSUPPORT_DYNAMIC_ALLOCATION == 0 )
        #error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0
#endif

/* A few bytes might be lost to byte aligning the heap start address. */
#define configADJUSTED_HEAP_SIZE        ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )

/*
 * Initialises the heap structures before their first use.
 */
static void prvHeapInit( void );

/* Allocate the memory for the heap. */
#if ( configAPPLICATION_ALLOCATED_HEAP == 1 )

/* The application writer has already defined the array used for the RTOS
* heap - probably so it can be placed in a special segment or address. */
        extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
#else
        static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
#endif /* configAPPLICATION_ALLOCATED_HEAP */


/* Define the linked list structure.    This is used to link free blocks in order
 * of their size. */
typedef struct A_BLOCK_LINK
{
        struct A_BLOCK_LINK * pxNextFreeBlock; /*<< The next free block in the list. */
        size_t xBlockSize;                                         /*<< The size of the free block. */
} BlockLink_t;


static const uint16_t heapSTRUCT_SIZE = ( ( sizeof( BlockLink_t ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~portBYTE_ALIGNMENT_MASK );
#define heapMINIMUM_BLOCK_SIZE        ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )

/* Create a couple of list links to mark the start and end of the list. */
static BlockLink_t xStart, xEnd;

/* Keeps track of the number of free bytes remaining, but says nothing about
 * fragmentation. */
static size_t xFreeBytesRemaining = configADJUSTED_HEAP_SIZE;

/* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */

/*
 * Insert a block into the list of free blocks - which is ordered by size of
 * the block.    Small blocks at the start of the list and large blocks at the end
 * of the list.
 */
#define prvInsertBlockIntoFreeList( pxBlockToInsert )                                                                                                                                                             \
        {                                                                                                                                                                                                                                                             \
                BlockLink_t * pxIterator;                                                                                                                                                                                                     \
                size_t xBlockSize;                                                                                                                                                                                                                    \
                                                                                                                                                                                                                                                                        \
                xBlockSize = pxBlockToInsert->xBlockSize;                                                                                                                                                                     \
                                                                                                                                                                                                                                                                        \
                /* Iterate through the list until a block is found that has a larger size */                                                                                                \
                /* than the block we are inserting. */                                                                                                                                                                            \
                for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
                {                                                                                                                                                                                                                                                     \
                        /* There is nothing to do here - just iterate to the correct position. */                                                                                             \
                }                                                                                                                                                                                                                                                     \
                                                                                                                                                                                                                                                                        \
                /* Update the list to include the block being inserted in the correct */                                                                                                        \
                /* position. */                                                                                                                                                                                                                         \
                pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;                                                                                                                         \
                pxIterator->pxNextFreeBlock = pxBlockToInsert;                                                                                                                                                            \
        }
/*-----------------------------------------------------------*/

void * pvPortMalloc( size_t xWantedSize )
{
        BlockLink_t * pxBlock, * pxPreviousBlock, * pxNewBlockLink;
        static BaseType_t xHeapHasBeenInitialised = pdFALSE;
        void * pvReturn = NULL;

        vTaskSuspendAll();
        {
                /* If this is the first call to malloc then the heap will require
                 * initialisation to setup the list of free blocks. */
                if( xHeapHasBeenInitialised == pdFALSE )
                {
                        prvHeapInit();
                        xHeapHasBeenInitialised = pdTRUE;
                }

                /* The wanted size must be increased so it can contain a BlockLink_t
                 * structure in addition to the requested amount of bytes. */
                if( ( xWantedSize > 0 ) &&
                        ( ( xWantedSize + heapSTRUCT_SIZE ) >    xWantedSize ) ) /* Overflow check */
                {
                        xWantedSize += heapSTRUCT_SIZE;

                        /* Byte alignment required. Check for overflow. */
                        if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) )
                                        > xWantedSize )
                        {
                                xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
                                configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
                        }
                        else
                        {
                                xWantedSize = 0;
                        }
                }
                else
                {
                        xWantedSize = 0;
                }


                if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
                {
                        /* Blocks are stored in byte order - traverse the list from the start
                         * (smallest) block until one of adequate size is found. */
                        pxPreviousBlock = &xStart;
                        pxBlock = xStart.pxNextFreeBlock;

                        while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )
                        {
                                pxPreviousBlock = pxBlock;
                                pxBlock = pxBlock->pxNextFreeBlock;
                        }

                        /* If we found the end marker then a block of adequate size was not found. */
                        if( pxBlock != &xEnd )
                        {
                                /* Return the memory space - jumping over the BlockLink_t structure
                                 * at its start. */
                                pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );

                                /* This block is being returned for use so must be taken out of the
                                 * list of free blocks. */
                                pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;

                                /* If the block is larger than required it can be split into two. */
                                if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
                                {
                                        /* This block is to be split into two.    Create a new block
                                         * following the number of bytes requested. The void cast is
                                         * used to prevent byte alignment warnings from the compiler. */
                                        pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxBlock ) + xWantedSize );

                                        /* Calculate the sizes of two blocks split from the single
                                         * block. */
                                        pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
                                        pxBlock->xBlockSize = xWantedSize;

                                        /* Insert the new block into the list of free blocks. */
                                        prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
                                }

                                xFreeBytesRemaining -= pxBlock->xBlockSize;
                        }
                }

                traceMALLOC( pvReturn, xWantedSize );
        }
        ( void ) xTaskResumeAll();

        #if ( configUSE_MALLOC_FAILED_HOOK == 1 )
                {
                        if( pvReturn == NULL )
                        {
                                extern void vApplicationMallocFailedHook( void );
                                vApplicationMallocFailedHook();
                        }
                }
        #endif

        return pvReturn;
}
/*-----------------------------------------------------------*/

void vPortFree( void * pv )
{
        uint8_t * puc = ( uint8_t * ) pv;
        BlockLink_t * pxLink;

        if( pv != NULL )
        {
                /* The memory being freed will have an BlockLink_t structure immediately
                 * before it. */
                puc -= heapSTRUCT_SIZE;

                /* This unexpected casting is to keep some compilers from issuing
                 * byte alignment warnings. */
                pxLink = ( void * ) puc;

                vTaskSuspendAll();
                {
                        /* Add this block to the list of free blocks. */
                        prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );
                        xFreeBytesRemaining += pxLink->xBlockSize;
                        traceFREE( pv, pxLink->xBlockSize );
                }
                ( void ) xTaskResumeAll();
        }
}
/*-----------------------------------------------------------*/

size_t xPortGetFreeHeapSize( void )
{
        return xFreeBytesRemaining;
}
/*-----------------------------------------------------------*/

void vPortInitialiseBlocks( void )
{
        /* This just exists to keep the linker quiet. */
}
/*-----------------------------------------------------------*/

static void prvHeapInit( void )
{
        BlockLink_t * pxFirstFreeBlock;
        uint8_t * pucAlignedHeap;

        /* Ensure the heap starts on a correctly aligned boundary. */
        pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT - 1 ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );

        /* xStart is used to hold a pointer to the first item in the list of free
         * blocks.    The void cast is used to prevent compiler warnings. */
        xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;
        xStart.xBlockSize = ( size_t ) 0;

        /* xEnd is used to mark the end of the list of free blocks. */
        xEnd.xBlockSize = configADJUSTED_HEAP_SIZE;
        xEnd.pxNextFreeBlock = NULL;

        /* To start with there is a single free block that is sized to take up the
         * entire heap space. */
        pxFirstFreeBlock = ( void * ) pucAlignedHeap;
        pxFirstFreeBlock->xBlockSize = configADJUSTED_HEAP_SIZE;
        pxFirstFreeBlock->pxNextFreeBlock = &xEnd;
}
/*-----------------------------------------------------------*/
